The ad doesn't appear to be present on every Apple Store page however -- we noticed it was absent from the London Regent Street shop, for instance. I called an Apple Store to ask and was told the scheme was available everywhere, but it might be worth calling your local Apple emporium and checking in advance if you're planning to trade-in.

What can I trade in?

Prices offered by Apple for trade ins will depend on the condition of the tablet you're trying to trade, as well as what kind of iPad you've got. Not all iPads are accepted -- the very first iPad, the most recent iPad mini with Retina display and the iPad Air are not eligible, unfortunately. You're unlikely to get anything close to what you initially paid for your Apple tablet, but the in-store trade-in could be a convenient option if you're planning on buying a new iPad anyway.